Developmental loss of speech perception: Exposure to and experience with a first language

Young infants perceive a variety of speech contrasts, even those that are not relevant in their own language environment. Evidence regarding the loss of perceptual ability with phonologically irrelevant contrasts is reviewed and a theoretical distinction is advanced. It is proposed that the perception of “fragile” contrasts is lost in infancy due to lack of exposure to particular sounds, while the perception of “robust” contrasts is lost around the onset of formal language training due to lack of experience with phonologically irrelevant contrasts. This distinction should provide a heuristic framework for future research on the development of speech perception.